This invention relates to a novel process for producing a modified conjugated diene polymer having excellent wear resistance and excellent mechanical characteristics, by polymerizing a conjugated diene with a lanthanum series rare earth metal catalyst and reacting the resulting reactive polymer with a specific compound. This invention further relates to a novel modified conjugated diene polymer produced according to said process.
In recent years, requirements of higher durability and longer life for component rubbers are increasing. Hence, it has become necessary to improve rubbers in such characteristics as wear resistance, mechanical properties, heat generation and the like.
Polybutadienes (rubbery polymer) obtained using a catalyst composed mainly of nickel, cobalt, titanium, etc. have been poor in wear resistance.
Meanwhile, known rubbery polymers having excellent wear resistance are polybutadienes produced using a lanthanum series rare earth metal catalyst. Of these polybutadienes, one produced using a lanthanum series rare earth metal catalyst proposed by the present inventors in Japanese Patent Application Kokai (Laid-Open) No. 57410/1983 has particularly excellent wear resistance.
Japanese Patent Application Kokai (Laid-Open) No. 40109/1985 describes that the reaction between (a) a polybutadiene produced using a lanthanum series rare earth metal catalyst and (b) a tetrahalomethane alone or in admixture with a specific organoaluminum compound enables production of a polybutadiene with an improved processability.
However, these polybutadienes are yet insufficient in wear resistance.